In top coat paint application onto automobiles, 2-coat-1-bake system has been widely used. This coating method comprises first applying a base coat paint to form a base coating film, applying onto the uncured base coating film a clear coat paint to form a clear coating film, and thereafter curing by heating the base coating film and clear coating film simultaneously. Thus obtained multilayer coating film excels in finished appearance such as gloss and depth.
Improvement in acid resistance of coating film has recently been in demand, and for meeting this demand, for example JP Hei 7 (1995)-133340A disclosed as a clear coat paint to be applied by 2-coat-1-bake system, a curable resin composition comprising polyepoxide, carboxyl group- and/or cyclic acid anhydride group-containing curing agent and a specific latent curing catalyst. Using this paint, coating film excelling in acid resistance can be obtained. When this clear coat paint is used in 2-coat-1-bake coating, however, there are such problems as that coating workability such as foaming resistance, sagging resistance and the like becomes insufficient in the occasions of thick textured coating, and that electrostatic coatability may become defective because high polarity of onium salt compound, which is among the latent curing catalyst used in the clear coat paint, lowers volume specific resistance of the paint.